A Ruthenium(II) complex as a potential luminescent switch-on probe for G-quadruplex DNA

This study aimed to synthesize two ruthenium(ii) complexes modified with aryl alkynes [Ru(phen)(TMSEPIP)](ClO) (1, phen = 1,10-phenanthrolin; TMSEPIP = 2-(2-trimethylsilylethylphenyl)imidazole[4,5f][1,10] phenanthroline) and [Ru(phen)(BEPIP)](ClO) (2, BEPIP = 2-(2-phenethylphenyl)imidazole[4,5f][1,10]phenanthroline) and evaluate their ability to act as luminescent probes of c-myc G-quadruplex DNA. It was discovered that the luminescence of 1 decreased in the presence of c-myc G-quadruplex DNA, while the luminescence of 2 clearly increased under the same conditions. Besides, in the presence of double-stranded DNA, the luminescence intensity of 1 and 2 showed little obvious change. It was interesting to find by atomic force microscopy that 1 could promote c-myc G-quadruplex DNA self-assembly to form a nano-network structure, while 2 could promote the formation of a nanowire structure. Further studies showed that 1 was inserted into the groove formed by base pairs A6-G8 and G21-T23 of c-myc G-quadruplex DNA, while 2 was inserted into the groove formed by G7-G9 and G22-A24. It is speculated that 2 can be developed as a potential luminescent switch-on probe through selectively recognizing and promoting self-assembly of c-myc G-quadruplex DNA.